Process and apparatus for producing a reformate by introducing methane

ABSTRACT

One exemplary embodiment can be a process for producing a reformate by combining a stream having an effective amount of methane and a stream having an effective amount of naphtha for reforming. Generally, the naphtha includes not less than about 95%, by weight, of one or more compounds having a boiling point of about 38-about 260° C. as determined by ASTM D86-07. Moreover, the process can include introducing the combined stream to a reforming reaction zone. Generally, the combined stream has a methane:naphtha mass ratio of about 0.03:1.00-about 0.10:1.00.

FIELD OF THE INVENTION

This invention generally relates to a process and an apparatus for producing a reformate.

DESCRIPTION OF THE RELATED ART

Naphtha reforming can produce a highly aromatic product for use as a gasoline product, a gasoline blending component, or a feedstock to produce other petrochemicals. However, the reforming process may produce significant levels of lighter byproducts including methane. Generally, the reduction of light byproducts is desired to allow for greater feedstock utilization and to make more desired compounds, such as aromatics, suitable for use in gasoline. Consequently, there is a desire to reduce net methane yield to reduce the amount of methane in the reformate.

SUMMARY OF THE INVENTION

One exemplary embodiment can be a process for producing a reformate by combining a stream having an effective amount of methane and a stream having an effective amount of naphtha for reforming. Generally, the naphtha includes not less than about 95%, by weight, of one or more compounds having a boiling point of about 38- about 260° C. as determined by ASTM D86-07. Moreover, the process can include introducing the combined stream to a reforming reaction zone. Generally, the combined stream has a methane:naphtha mass ratio of about 0.03:1.00-about 0.10:1.00.

Another exemplary embodiment can be a process for producing a reformate by combining a stream rich in methane and a stream rich in naphtha. Generally, the naphtha has not less than about 95%, by weight, of one or more compounds having a boiling point of about 38-about 260° C. as determined by ASTM D86-07. The process can include introducing the combined stream to a reforming reaction zone. Typically, the combined stream has a methane:naphtha mass ratio of about 0.03:1.00-about 0.10:1.00 and a pressure less than about 5,000 kPa.

A further exemplary embodiment may be a process. The process can include combining a stream including substantially methane and a stream including substantially naphtha. Typically, the naphtha has not less than about 95%, by weight, of one or more compounds having a boiling point of about 38-about 260° C. as determined by ASTM D86-07. Generally, the process includes introducing the combined stream to a reforming reaction zone.

The embodiments disclosed herein can provide a reduction in the production of methane in a reaction reforming zone effluent by co-feeding methane. Thus, the production of methane can be reduced and the production of desired products can be increased. In addition, co-feeding methane may be more advantageous as compared to co-feeding other light hydrocarbons, particularly if the existing infrastructure allows using available methane as a co-feed with little or no additional capital expenditure.

DEFINITIONS

As used herein, the term “stream” can be a stream including various hydrocarbon molecules, such as straight-chain, branched, or cyclic alkanes, alkenes, alkadienes, and alkynes, and optionally other substances, such as gases, e.g., hydrogen, or impurities, such as heavy metals, and sulfur and nitrogen compounds. The stream can also include aromatic and non-aromatic hydrocarbons. Moreover, the hydrocarbon molecules may be abbreviated C1, C2, C3 . . . Cn where “n” represents the number of carbon atoms in the one or more hydrocarbon molecules. Furthermore, a superscript “+” or “−” may be used with an abbreviated one or more hydrocarbons notation, e.g., C3⁺ or C3⁻, which is inclusive of the abbreviated one or more hydrocarbons. As an example, the abbreviation “C3⁺” means at least one hydrocarbon molecule of three and/or more carbon atoms. Also, methane can be abbreviated “C1”, and propane can be abbreviated “C3”.

As used herein, the term “zone” can refer to an area including one or more equipment items and/or one or more sub-zones. Equipment items can include one or more reactors or reactor vessels, heaters, exchangers, pipes, pumps, compressors, and controllers. Additionally, an equipment item, such as a reactor, dryer, or vessel, can further include one or more zones or sub-zones.

As used herein, the term “rich” can mean an amount of generally at least about 50%, and preferably about 70%, by mole, of a compound or class of compounds in a stream.

As used herein, the term “substantially” can mean an amount of generally at least about 80%, preferably about 90%, and optimally about 99%, by mole, of a compound or class of compounds in a stream.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graphical depiction of net methane yield versus C5 non-aromatics conversion for co-feeds of methane and propane.

DETAILED DESCRIPTION

Generally, the embodiments disclosed herein can provide a co-feed of a stream including an effective amount of methane for modifying one or more reforming reactions. In addition, the stream can be preferably rich in methane or even substantially methane. What is more, the methane stream can include at least about 50%, by mole, methane or higher amounts including at least about 60%, at least about 70%, at least about 80%, at least about 90%, or even about 100%, by mole, methane. The stream can be obtained from recycling methane obtained from downstream fractionation units from a reforming reaction zone or obtained from separate units within a refinery or petrochemical processing facility.

Typically, this stream including methane is combined with a stream including an effective amount of naphtha for facilitating one or more reforming reactions. In addition, the naphtha stream can be rich in naphtha or substantially naphtha. What is more, the naphtha stream can include at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, or even about 100%, by mole, naphtha. Generally, the naphtha stream has at least about 95%, by weight, of one or more compounds having a boiling point of about 38-about 260° C.

Furthermore, a stream including an effective amount of hydrogen for facilitating one or more reforming reactions can be combined with the methane stream and the naphtha stream. Generally, the hydrogen stream is rich in or substantially hydrogen. The stream including hydrogen can be recycled from the downstream units, such as a separation vessel.

These three streams can form a combined stream provided to a reforming reaction zone. The combined stream can have a methane:naphtha mass ratio of about 0.03:1.00-about 0.10:1.00, preferably about 0.06:1.00-about 0.10:1.00. In addition, the combined stream may have a hydrogen:naphtha mole ratio of no more than about 10:1, and preferably about 2:1-about 8:1. Afterwards, the combined stream can be provided to a reforming reaction zone.

The reforming reaction zone can include at least one reforming reactor, preferably a plurality of reforming reactors operating in serial and/or parallel. The reforming reaction zone can operate under any suitable conditions and include any suitable equipment. An exemplary reforming reaction zone is disclosed by Dachos et al., UOP Platforming Process, Chapter 4.1, Handbook of Petroleum Refining Processes, editor Robert A. Meyers, 2nd edition, pp. 4.1-4.26 (1997). The reforming reaction can dehydrogenate compounds such as naphthenes, can isomerize paraffins and naphthenes, can dehydrocyclicize paraffins, and/or hydrocrack and dealkylate paraffins. The reforming reaction zone can include other equipment such as furnaces and a combined feed heat exchanger.

The one or more reforming reactors can include any suitable reforming catalyst, such as a catalyst including a group VIII metal, a group IVa component, such as tin, and an inorganic oxide binder, such as alumina, magnesia, zirconia, chromia, titania, boria, thoria, phosphate, zinc oxide, silica, or a mixture thereof. Suitable reforming reaction catalysts are disclosed in, for example, US 2006/0102520 A1.

The reforming reaction zone can have a temperature of about 300-about 550° C., preferably about 470-about 550° C., and optimally about 500-about 550° C. The pressure in the reaction zone can be less than about 5,000 kPa, preferably the pressure can be about 340-about 5,000 kPa, and more preferably may be about 340-660 kPa. Generally, a liquid hourly space velocity (LHSV) based on the naphtha feed is about 0.1-about 20 hr⁻¹, preferably about 0.5-about 5.0 hr⁻¹. The resulting reforming reaction zone effluent can include a minimal amount of methane, such as no more than 0.5%, by weight, methane.

In addition, downstream units can separate the reforming reaction zone effluent into various products, such as removing the excess light gases such as hydrogen and optionally, recycling such hydrogen to the reforming reaction zone. Moreover, downstream fractionation units can include a de-ethanizer, a de-propanizer, and/or a debutanizer to separate out various light end fractions. In some preferred embodiments, the downstream fractionation may include the separation of methane and recycling such molecules for combining with the naphtha stream to be fed into the reforming reaction zone. Alternatively, a stream having sufficient amounts of methane may be obtained from natural gas or other petrochemical processing units having an existing methane-rich product stream. As an example, a naphtha hydrocracker can provide a suitable methane stream.

Although it is anticipated that the methane stream can be obtained from other sources within the refinery or from downstream fractionation units from the reforming reaction zone, it is contemplated that the methane can be present in the hydrogen stream combined with the naphtha stream. If the methane is present in sufficient quantities, the methane in the hydrogen stream can provide the requisite mole ratio with respect to the naphtha stream to facilitate reforming reactions.

EXAMPLES

The following examples are intended to further illustrate the disclosed embodiments. These illustrations of the embodiments are not meant to limit the claims to the particular details of these examples. These examples can be based on engineering calculations and actual operating experience with similar processes.

Tests are conducted of comparing a co-feed of methane and naphtha, and a co-feed of propane and naphtha, which hereinafter may be referred to as, respectively, as a co-feed of methane or a co-feed of propane. Each test is conducted in a pilot plant using the same reforming catalyst made in accordance with US 2006/0102520 A1. The pilot plant is operated to minimize catalyst de-activation during the test. The catalyst has a chloride content of about 1% by weight. The feedstock is a commercial naphtha with an endpoint of 160° C. The methane and propane are provided as pure components. The feed contains 1.1 weight ppm sulfur on a naphtha plus methane basis for the methane co-feed or a naphtha plus propane basis for the propane co-feed. These conditions can provide a sulfur level at the reactor inlet typical of a commercial unit reactor. The temperature of the reactor is varied from 510-540° C. to obtain performance data at different conversion levels of the feedstock. The parameters for the co-feed of C1 and the co-feed of C3 are depicted below in Table 1:

TABLE 1 Parameter C1 Co-Feed C3 Co-Feed C1 or C3 to Naphtha Mass Ratio 0.072 0.20 (gram/gram) C1 or C3 to Naphtha Mole Ratio 0.488 0.488 (mole/mole) LHSV Based on Naphtha 2.75 2.75 (hr⁻¹) LHSV on Naphtha + C1 or C3 Not Applicable 3.55 (hr⁻¹) Hydrogen:Hydrocarbon Mole Ratio Based 8.0 8.0 on Naphtha (mole/mole) Hydrogen:Naphtha + C3 Mole Ratio 8.0 5.4 (mole/mole) Pressure (kPa) 446 446

The following formula is used to calculate the yield of, respectively, methane, propane, or hydrogen (each “selected species” collectively abbreviated “ss”) in the naphtha co-feed:

Y _(ss)=(P _(ss) −L _(ss))/N*100%

-   Y_(ss)=net mass yield methane, propane, or hydrogen based on a     naphtha feed; -   P_(ss)=mass flow methane, propane, or hydrogen in the reactor     effluent; -   L_(ss)=mass flow of a methane or propane co-feed or a hydrogen feed;     and -   N=mass flow of a naphtha feed.

The following formula is used to calculate the yield of species (i) in the reactor product where (i) is a component other than methane, propane, or hydrogen in the reactor effluent:

Y _(i) =P _(i) /N*100%

-   Y_(i)=net mass yield of species (i) based on the naphtha feed; -   P_(i)=mass flow of species (i) in the reactor effluent; and -   N=mass flow of a naphtha feed.

Referring to FIG. 1, a comparison of the yields of methane for the co-feed of methane and the co-feed of propane is depicted. The yields for the co-feeds methane and propane are calculated using the same experimental computations and statistical methods. A line of best fit is drawn through the data points.

The co-feed of methane produced a reduced methane yield based on the naphtha feed in the reforming reaction zone effluent as compared to the co-feed of propane. Co-feeding methane can be particularly beneficial if a manufacturing or refining facility has an existing source of methane that can be provided to the reforming reaction zone with little or no additional capital expenditure. Thus, the data can demonstrate the significant and unexpected results of providing a co-feed of methane to reduce the production of methane in the reforming reaction zone effluent.

Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever.

In the foregoing, all temperatures are set forth in degrees Celsius, all parts and percentages are by weight, and all pressure units are absolute, unless otherwise indicated.

From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions. 

1. A process for producing a reformate by combining a stream comprising an effective amount of methane and a stream comprising an effective amount of naphtha for reforming wherein the naphtha has not less than about 95%, by weight, of one or more compounds having a boiling point of about 38-about 260° C. as determined by ASTM D86-07, comprising: A) introducing the combined stream to a reforming reaction zone wherein the combined stream has a methane:naphtha mass ratio of about 0.03:1.00-about 0.10:1.00.
 2. The process according to claim 1, wherein the combined stream has a methane:naphtha mass ratio of about 0.06:1.00-about 0.10:1.00.
 3. The process according to claim 1, wherein the reforming reaction zone has a temperature of about 300-about 550° C.
 4. The process according to claim 1, wherein the reforming reaction zone has a pressure less than about 5,000 kPa and a liquid hourly space velocity based on a naphtha feed of about 0.1-about 20 hr⁻¹.
 5. The process according to claim 1, wherein the reforming reaction zone has a pressure of about 340-about 660 kPa and a liquid hourly space velocity based on a naphtha feed of about 0.5-about 5.0 hr⁻¹.
 6. The process according to claim 1, further comprising providing a stream rich in hydrogen to the reforming reaction zone.
 7. The process according to claim 1, wherein the stream comprising methane further comprises hydrogen.
 8. The process according to claim 6, wherein the stream comprising methane is rich in methane.
 9. The process according to claim 7, wherein the reforming reaction zone has a pressure of about 340-about 660 kPa and a liquid hourly space velocity based on a naphtha feed of about 0.5-about 5.0 hr⁻¹, and the combined stream has an isopentane:naphtha mass ratio of about 0.06:1.00-about 0.10:1.00.
 10. The process according to claim 9, wherein the reforming reaction zone has a temperature of about 470-about 550° C.
 11. The process according to claim 9, wherein a reforming reaction zone effluent comprises no more than about 0.5%, by weight, methane.
 12. The process according to claim 11, wherein the reforming reaction zone has a temperature of about 500-about 550° C.
 13. The process according to claim 1, wherein a reforming reaction zone effluent comprises no more than about 0.5%, by weight, methane.
 14. The process according to claim 1, wherein the methane is provided by at least a portion of a stream recycled from downstream fractionating of the reforming reaction zone effluent.
 15. A process for producing a reformate by combining a stream rich in methane and a stream rich in naphtha wherein the naphtha has not less than about 95%, by weight, of one or more compounds having a boiling point of about 38-about 260° C. as determined by ASTM D86-07, comprising: A) introducing the combined stream to a reforming reaction zone wherein the combined stream has a methane:naphtha mass ratio of about 0.03:1.00-about 0.10:1.00 and a pressure less than about 5,000 kPa.
 16. The process according to claim 15, wherein the combined stream has a methane:naphtha mass ratio of about 0.06:1.00-about 0.10:1.00.
 17. A process, comprising: A) combining a stream comprising substantially methane and a stream comprising substantially naphtha wherein the naphtha has not less than about 95%, of one or more compounds by weight, having a boiling point of about 38-about 260° C. as determined by ASTM D86-07; and B) introducing the combined stream to a reforming reaction zone.
 18. The process according to claim 17, wherein the combined stream has a methane:naphtha mass ratio of about 0.03:1.00-about 0.10:1.00.
 19. The process according to claim 17, wherein the combined stream has a methane:naphtha mass ratio of about 0.06:1.00-about 0.10:1.00.
 20. The process according to claim 17, wherein the reforming reaction zone has a pressure of about 340-about 660 kPa. 